Touri Asked:
Can​ ​you​ ​please​ ​tell​ ​me​ ​which​ ​IEC​ ​article​ ​bans​ ​the​ ​use​ ​of​ ​carbonaceous​ ​backfills​ ​for​ ​earth​ ​electrodes?

Our Answer:
E&S Grounding ​are​ ​not​ fans​ ​of​ ​using​ ​carbonaceous​ ​breeze​ ​or​ ​coke​ ​breeze​ ​around​ ​our​ ​earthing​ ​electrodes​ ​as​ ​it​ ​tends​ ​to​ ​corrode​ ​electrodes. Before​ ​we​ ​go​ ​any​ ​further,​ ​it​ ​is​ ​worth​ ​noting​ ​that​ ​there​ ​are​ ​differing​ ​terminologies​ ​used​ ​with​ ​in​ ​the​ ​industry​ ​for​ ​what​ ​”Coke​ ​Breeze”​ ​and​ ​”Carbonaceous​ ​Breeze”​ ​even​ ​is. There​ ​are​ ​two​ ​main​ ​types​ ​of​ ​Coke:​ ​

1).​ ​Coke​ ​Fuel,​ ​and​
​2).​ ​Petroleum​ ​Coke – Which can​ ​be​ ​further​ ​categorized​ ​into​ ​4 sub-types:​

• ​Needle​ ​coke,​ ​
• Honeycomb​ ​coke,​ ​
• Sponge​ ​coke​,
• Shot​ ​coke.

In​ ​the​ ​grounding​ ​and​ ​earthing​ ​industry,​ ​we​ ​are​ ​generally​ ​interested​ ​in​ ​Refined​ ​Honeycomb​ ​Coke.​ ​​ ​This​ ​is​ ​because​ ​refined​ ​honeycomb​ ​coke​ ​has​ ​been​ ​cooked​ ​at​ ​high​ ​temperatures​ ​leaving​ ​it​ ​with​ ​a​ ​very​ ​low​ ​level​ ​of​ ​sulfur,​ ​a​ ​low​ ​coefficient​ ​of​ ​thermal​ ​expansion,​ ​and​ ​very​ ​low​ ​in​ ​electrical​ ​conductivity. Unfortunately,​ ​we​ ​do​ ​not​ ​see​ ​a​ ​very​ ​clear​ ​definition​ ​within​ ​the​ ​grounding​ ​and​ ​earthing​ ​industry​ ​about​ ​what​ ​types​ ​of​ ​coke​ ​/​ ​carbonaceous​ ​breeze​ ​is​ ​acceptable.

In​ ​BS​ ​7430:2011+A1:2015​ ​Article​ ​9.2.2​ ​we​ ​find​ ​that​ ​the​ ​code​ ​actually​ ​prohibits​ ​using​ ​any​ ​form​ ​of​ ​coke​ ​breeze​ ​at​ ​all.

However,​ ​we​ ​find​ ​the​ ​following​ ​statement​ ​int​ ​Motorola​ ​R56​ ​2005​ ​and​ ​a​ ​similar​ ​statement​ ​in​ ​​ ​FAA​ ​Std​ ​019: “The​ ​use​ ​of​ ​charcoal​ ​or​ ​petroleum​ ​based​ ​coke​ ​breeze​ ​is​ ​not​ ​recommended​ ​as​ ​it​ ​may​ ​result​ ​in​ ​rapid​ ​corrosion​ ​of​ ​copper​ ​electrodes​ ​and​ ​copper​ ​conductors​ ​(BS​ ​7430:1998,​ ​clause​ ​8.5;​ ​BS​ ​6651:1999,​ ​clause​ ​18.4.2;​ ​and​ ​FAA​ ​STD​ ​019d-2002,​ ​section​ ​3.8.3.5).​ ​Charcoal​ ​and​ ​petroleum​ ​based​ ​coke​ ​typically​ ​contains​ ​high​ ​levels​ ​of​ ​sulfur,​ ​which​ ​in​ ​the​ ​presence​ ​of​ ​moisture​ ​will​ ​accelerate​ ​corrosion.​ ​Coke​ ​breeze​ ​derived​ ​from​ ​coal​ ​in​ ​coke​ ​ovens​ ​is​ ​generally​ ​considered​ ​acceptable;​ ​all​ ​the​ ​corrosives​ ​and​ ​volatiles​ ​have​ ​been​ ​cooked​ ​off​ ​at​ ​extremely​ ​high​ ​temperatures​ ​(FAA​ ​STD​ ​019d-2002,​ ​section​ ​3.8.3.5).”

As​ ​you​ ​can​ ​see​ ​by​ ​looking​ ​at​ ​the​ ​two​ ​differing​ ​standards​ ​above,​ ​there​ ​are​ ​some​ ​differences​ ​between​ ​the​ ​standards.​ ​ ​The​ ​IEC​ ​simply​ ​bans​ ​all​ ​form​ ​of​ ​coke​ ​/​ ​carbonaceous​ ​breeze,​ ​while​ ​the​ ​American​ ​code​ ​makers​ ​differentiate​ ​the​ ​use​ ​of​ ​low-sulfur​ ​coke​ ​breeze​ ​as​ ​being​ ​acceptable.

However,​ ​in​ ​the​ ​2007​ ​”National​ ​Electrical​ ​Grounding​ ​Research​ ​Project”​ ​conducted​ ​by​ ​the​ ​Fire​ ​Protection​ ​Research​ ​Foundation,​ ​we​ ​find​ ​mixed​ ​results​ ​for​ ​all​ ​forms​ ​of​ ​backfill​ ​material​ ​when​ ​compared​ ​to​ ​native​ ​earth.​ ​​ ​This​ ​research​ ​project​ ​subjected​ ​numerous​ ​differing​ ​electrode​ ​types,​ ​in​ ​multiple​ ​soil​ ​conditions,​ ​to​ ​various​ ​earthing​ ​enhancement​ ​products,​ ​over​ ​a​ ​10​ ​to​ ​17​ ​year​ ​time​ ​frame​ ​and​ ​documented​ ​the​ ​results.​ ​​ ​In​ ​some​ ​cases​ ​coke​ ​breeze​ ​products​ ​only​ ​caused​ ​minimal​ ​corrosion​ ​to​ ​the​ ​electrodes,​ ​and​ ​in​ ​other​ ​cases​ ​it​ ​caused​ ​catastrophic​ ​damage​ ​to​ ​the​ ​electrodes.​ ​​ ​This​ ​included​ ​coke​ ​breeze​ ​products​ ​that​ ​met​ ​the​ ​low-sulfur​ ​requirements.

E&S​ ​generally​ ​recommends​ ​that​ ​you​ ​simply​ ​install​ ​your​ ​below-grade​ ​earthing​ ​and​ ​grounding​ ​systems​ ​in​ ​native​ ​soil​ ​or​ ​clean​ ​fill.​ ​​ ​No​ ​backfill​ ​materials​ ​required.

The Engineering Experts at E&S Grounding Solutions